week5:Chemical bonding, electronegativity, weak bonds Flashcards
What leads to the formation of chemical bonds?
The tendency of atoms to react with other atoms
What is a covalent bond?
The bonding that occurs between two non-metals sharing their electrons.
What is an ionic bond?
Transfer of electrons
Only electrons involved in bonding are the?
Valence electrons
What is the difference between Lewis dot symbol and electron configuration
electron configuration shows all the electrons in an atom. Lewis dot only shows the valence electrons.
Why do chemical bonds form?
To obtain stability. Bounded atoms have a lower energy state thus, are more stable.
State the octet rule.
When forming a chemical bond, an element loses, gains, or shares electron(s), in order to have 8 electrons in its outermost shell (or only 2 electrons for elements near He.
What theory states that the driving force of covalent bond formation derives from the octet rule?
Valence bonding theory
What is a non-polar covalent bond?
Covalent bonding between atoms with same electronegativity
What is a polar covalent bond?
Covalent bonding between atoms with different electronegativity
what determines bonding strength?
Attraction of bonding electrons by both nuclei
where on the energy distance graph indicates bond length
minimum of energy
What is molecular orbital
A new orbital that is formed to accommodate electrons from the atoms forming the molecule, a region where all their electrons are most likely to be found. It is a combination of atomic orbitals.
How is the bonding interaction achieved in terms of molecular orbital
The bonding interaction is achieved because
the energy of the molecular orbital is lower
(more favorable) than the energy of the atomic
orbital
What is a sigma molecular orbital?
Molecular orbitals that are symmetrical about
the axis of the bond (head to head overlap of
atomic orbitals)
Molecular orbital theory predicts that:
The combination of two atomic orbitals leads to the formation of two molecular orbitals named bonding molecular orbital and antibonding molecular orbital
Bonding molecular orbitals ?
have a lower energy than the atomic orbitals from which they were formed
Anti-bonding orbitals?
they have a higher energy than the atomic orbitals from which they were formed
Electrons occupy Anti-bonding molecular orbitals while bonding molecular orbitals remain empty, true or false?
False!!
explain hybrid orbitals
https://www.youtube.com/watch?v=vHXViZTxLXo
What is a coordinate (dative) covalent bond
A covalent bond between two atoms where one of the atoms provides both electrons for sharing
*refer lecture 2c
how to calculate formal charge
formal charge=valence electrons - nonbonded electrons - 1/2 bonded electrons
Describe the hydrogen bond
When hydrogen bonds to a highly electronegative atom causes the molecule to have a permanent dipole, in which hydrogen is partially postive, thus causing it to be attracted to other electronegative atoms
What are some properties of hydrogen bonds?
Elevated boiling temperature
High values of latent heat of fusion and vaporization, specific heat capacity
What are some biological significance of hydrogen bonding?
-Protein shaping
-Interaction between antibodies and antigen
-Hold complemenatry strands of DNA, participates in RNA three dimensional structure
What are the types of van der Waals interactions?
-Dipoles (permanent dipole, instantaneous dipole, Induced dipole)
-London dispersion force-temporarily polar from a neighboring induced dipole
